This invention relates to a disk cartridge, such as a floppy disk, containing a magnetic disk medium and to a method of manufacturing the same.
A conventional disk cartridge comprises a magnetic disk medium and upper and lower shells forming a space to receive the magnetic disk medium. The upper and the lower shells are provided with upper and lower head windows, respectively, to permit access to the magnetic disk medium by a pair of magnetic heads. The magnetic disk medium is made of a magnetic material having flexibility. A liner is attached to an inner surface of each of the upper and the lower shells. The liner serves to remove fine dust attracted onto the surface of the magnetic disk medium. Therefore, the liner is preferably arranged as close as possible to the surface of the magnetic disk medium.
The conventional disk cartridge has a first problem in that the magnetic disk medium is readily wrinkled as will later be described in detail.
Furthermore, the conventional disk cartridge has a second problem in that, if the liner is too close to the magnetic disk medium, a torque loss will be caused to reduce a torque for rotating the magnetic disk medium. With an increase in torque loss, data writing/reading operations upon the magnetic disk medium become unstable and unreliable.
On the other hand, an apparatus for accessing the disk cartridge described above by the use of magnetic heads is called a disk drive. The disk drive comprises a disk holder unit for receiving the disk cartridge, and upper and lower magnetic heads for accessing the magnetic disk medium through the upper and the lower head windows of the disk cartridge. The upper and the lower magnetic heads are held by a carriage assembly.
More specifically, the carriage assembly comprises upper and lower carriages. The upper and the lower carriages hold the upper and the lower magnetic heads at their top ends, respectively. If no disk cartridge is received in the disk drive, it is necessary to separate the upper magnetic head from the lower magnetic head. For this purpose, when no disk cartridge is received in the disk drive, an arm attached to the upper carriage is engaged with the disk holder unit so that the top end of the upper carriage is lifted up. It is noted here that the disk cartridge has a thickness of about 3.3 mm if it is a floppy disk. Therefore, in the conventional disk drive for the floppy disk, the top end of the upper carriage must be lifted up in a range between about 3.5 and 3.6 mm. Thus, in the disk drive for the disk cartridge, the upper magnetic head must be displaced over a distance greater than the thickness of the disk cartridge. For this purpose, a vertical movement mechanism for vertically moving the upper magnetic head is required. The vertical movement mechanism is subjected to a heavy load. Since the displacement of the upper magnetic head is relatively large, a head load pressure downwardly applied to the upper magnetic head is not stable. This third problem results from the structure of the disk cartridge.